Discharge controlling means for discharge lamps



DISCHARGE CONTROLLING MEANS FOR DISCHARGE LAMPS Filed Aug. 25, 1952 INVENTOR Patented Nov. 10, 1936 t I UNITED STATESPATENT OFFICE DISCHARGE CONTROLLING MEANS FOR -DISCHARGE LAMPS Chester H. Braselton, New York, N. Y., assignor to Sirian Lamp Company, Newark, N. J a corporation of Delaware Application August 25, 1932, Serial No. 630,379

7 Claims. (Cl. 176-1) This invention relates to electric lamps and of another embodiment of the electron emitting particularly to that type in which a discharge element; occurs through a gaseous medium. In order to properly illustrate the invention a In my prior filed application, now Patent No. lamp has been shown in Fig. 1 comprising a 5 2,007,919, issued July 5, 1935, I disclosed a new tubular bulb or envelope I formed of suitable type of lamp in which an electron emitting eletransparent material such as glass and having a ment is energized by an electric current in the press II at O e end d a Second press at the presence of an ionizablegas having a certain other for supporting an elongated electron pressure. When the conditions are right as to emitting element l3 on the axis of the envelope. l0 pressure, voltage impressed upon the element, The electron emitting element I3 may be atand the character of the gas used, a halo is taehed to uppo d l4 a d I5 ea ed in th formed around the element extending from one pr ss s II a d II resp tiv ly and p vid d end to the other and standing out from the filapeet v y W ead- W res l5 a d Whi e ment a distance in the neighborhood of of an any desirable form of electron emitting element inch. As the pressure of the gas is increased in may be used Wit the invention I y prefer to 15 the envelope the halo tends to hug the filament form said element of a concentrated coil I8 of closer while if the pressure is decreased the halo hi hly r fractory Wir S h as t n y will tend to extend further from the element. denum, tanta u the like, as Shown in Also as the voltage is increased across the elecwith a coating IS on the surface of the coil formed tron emitting element there isa tendency for the O a material g v a rich electron emission- 20 discharge or halo to increase in diameter while This Co t y b y of the Well known e cif the voltage is lowered the halo gradually falls n emitting m ri l su h a n o m e of back against the filament until it disappears enthe Oxides barium, Strontium, calcium, t tirely, w t given pressure therefore t is like, held on to the coil with a suitable binder necessary to keep the voltage at a constant figure Whlch a be driven Off when the element is 25 in order to maintain the discharge at a constant treated W101 to Sealing The coatmg of elec- Size tron emitting material may, however, be applied It is one of the objects of the present invention F h mdivldua'l of t wire as mdmaifed to provide auxiliary means for controlling the m Flgj5"where the C011 20 15 shown P wlth size of the discharge so that it will not be det emlttmg material 9 the meteml may be 30 pendent entirely upon the Voltage across the incorporated in the wire itself, as in the case of ment or the pressure of the gas used the well known thoriated tungsten filament wh1ch Another object of the invention is to provide a may be made by treatmg tungstic and horium nitrate. fixed restricted path for the discharge in a lamp t whereby the size of the discharge may be deter on one of the presses as the press Whlch 1S somewhat thickened for that purpose, I mount gagg independently of the Voltage and gas presa plurality of support rods 22 which extend to about the center of the envelope and adjacent the Other objects of the invention and objects 2 relating particularly to the construction and walls thereof. The ends of the support rods 2 40 are formed into small hooks 23 and engage a 40 assembly of vanous parts W111 be apparent disc 24 of mica, lava, or other suitable insulating as the .descnptlon .pmceeds' material, securing it in a plane substantially per- The f f is {nustrated m the accompany pendicular to the axis of the lamp and with its mg drawmg m whmh: edges in close proximity with the inner sides of Fig. 1 is a sectional side elevational ViBW Of a t wall of t lamp. The disc 24 has a hole 25 45 lamp embodymg the Invention; in the center thereof which has a diameter the 2 is a sectional end View taken on the line same size as the desired discharge and the elecof 1; tron emitting element passes through this hole,

3 is a sectional side elevational view of a as clearly indicated in Figs. 1 and 2. When the lamp illustrating another embodiment of the in discharge rs it must pass through the hole 50 Ve 25 as' the remainder of the disc substantially -M891 enlarged Side elevetional VieW'partlY closes oil the interior of the envelope, and the in section of one of the electron emitting eledischarge is thus defined by the hole. ments; and The envelope may be filled with a suitable Fig. 5 is an enlarged sectional elevational view ionizable gas but I may prefer to use one or more 55 helium, krypton, and xenon or one or more of certain metal vapors such as the vapors of mercury, caesium, sodium, rubidium, and the like or mixtures of any of such gases or vapors. I have found that the pressure of the gas should be in the neighborhood of 200 mm. of mercury.

With the elements mounted in the envelope as described above, the envelope may be connected to a vacuum pump in the usual manner and an oven may be placed over it to raise the temperature thereof so as to drive out occluded gases from the various parts of the device. The glass and associated parts maybe heated to a temperature in the neighborhood of 400 C. or to as high a temperature as the glass will stand without softening in order to remove all of these gases. Current may also be run through the filament to raise the temperature thereof to about 600 C. This heat is continued until a high vacuum of approximately .5 micron is obtained and all of the gases have been removed from the envelope, which is evidenced by no fluorescence when a high tension current from an induction coil is directed against the walls of the bulb. Current may then be increased through the filament and the temperature thereof slowly raised until it is a bright red when the temperature will be about 800 C. This drives out any binder in the electron emitting material and also certain occluded gases which have not yet been removed. The pump continues to remove from the envelope gases which are driven out of elements or other parts.

When no more gas is found in the envelope'the oven may be raised and the filament heated to slightly less than 1200 C. for a short time to drive out any other occluded gases or vapors which may be left. The pump may then be shut off and a slight amount of an inert gas, such as neon, at a pressure of about 1 mm. may be admitted to the envelope and the filament current turned on again. This causes reddish spots of discharge to appear on the element or other parts of the lamp which gradually increase in size until a diffused glow appears inside of the bulb substantially filling it, and this tends to activate the electron emitting coating to raise the electron emitting efficiency thereof. This process should take about 10 minutes but if white spots appear it is an indication that other gases are present and the envelope should be exhausted again and the process repeated.

When the activation is completed the pump may again be connected to the envelope and the gas pumped out until a high vacuum is obtained. The filament circuit may then be disconnected and the pump turned off and about 50 mm. 01' neon gas admitted into the envelope followed by about 150 mm. of argon. The bulb may then be sealed off and is ready for use.

When the lamp is connected in a circuit by means of the lead-in wires I6 and II the element I3 is energized and the temperature thereof raised until it reaches a high rate of electron emissivity. Thereupon the discharge forms, extending outwardly from the filament and passing from end to end thereof through the hole in the insulating disc 24. This discharge consists of luminous gas having the appearance of a bright white flame and its size is determined by the size of the opening in the disc 24. Inasmuch as the hole 25 in the disc determines the size of the path for the discharge it cannot increase any larger beyond the dia' 'eter of the hole and is,

therefore, controlled and prevented from carrying more current than is desired.

In Fig. 3 another embodiment of the invention is shown, wherein the disc 26, which is similar to the disc 24, has a hole 2! therein to control the size of the discharge and is mounted directly on the wall 28 of the envelope 29. For this purpose suitable extensions 30 are provided on the inner Wall of the bulb at about the center thereof ,having grooves 3! to receive the disc which may be sprung into position in the glass before the electron emitting element is inserted. The operation of this construction is similar to that already described.

Many other modifications of the invention may be resorted to without departing from the spirit thereof and I do not, therefore, desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claim and secure by Letters Patent is:

1. In a device of the class described an envelope, a partition having an opening therein mounted within said envelope and dividing saidenvelope into two compartments interconnected by said opening, an electron emitting element containing one or more oxides of the alkaline earth metals extending through said opening and having one end in one compartment and the other end in the other, and a mixture of neon and argon gases at a pressure of substantially 200 mm. of mercury within said envelope, said electron emitting element being adapted to be energized by the passage of electric current therethrough.

2. In a device of the class described an envelope, a partition having an opening therein mounted within said envelope and forming two compartments within said envelope inter-connected by said opening, an electron emitting element containing one or more oxides of the alkaline earth metals extending through said opening and having one end in one compartment and the other end in the other, and an ionizable gas having a pressure of substantially 200 mm. of mercury within said envelope, said electron emitting element being adapted to be energized by the passage of electric current therethrough.

3. In a device of the class described a tubular envelope, a filamentary conductor axially positioned therein, an ionizable gas within the envelope, means including one or more oxides of the alkaline earth metals for producing a halo about said conductor when the conductor is heated to luminous temperatures by the passage of electric current therethrough, said halo being variable in diameter with variation of applied voltage to the terminals of the conductor, and means for maintaining a section of said halo constant with variations of applied voltage, said halo producing means constituting the sole terminal source of the discharge.

4. In a device of the class described a tubular envelope, an axially positioned conductor therein, means including one or more oxides of the alkaline earth metals to produce a halo about said conductor, said halo having a diameter variable with the voltage applied to the terminals of the conductor, and means to maintain a section of said halo uniform in diameter irrespective of variations in the voltage at the conductor terminals, said halo producing means constituting the sole terminal source of the discharge.

5. In a device of the class described a tubular envelope, 2. filament conductor axially positioned therein, an ionizable gas within the envelope, a coating of electron emitting substance containing one or more oxides of the alkaline earth metals on said conductor adapted when heated to cause the formation of a halo about the conductor which halois variable in diameter with the variation of voltage applied to the conductor terminals, and means for maintaining a section of said halo constant with variation of applied voltage, said coating constituting the sole terminal source of the discharge.

6. In a device of the class described a tubular envelope, a filament conductor axially positioned therein, an ionizable gas within the envelope, a coating of electron emitting substance containing one or more oxides of the alkaline earth metals on said conductor adapted when heated to cause the formation of a halo about the conductor which halo is variable in diameter with the variation of voltage applied to the conductor terminals, and a plate positioned transversely 01' said conductor said plate having an aperture including.

said conductor, said coating constituting the sole terminal source of the discharge.

7. In a device of the class described an elongated electron emitting element containing one or more oxides of the alkaline earth metals, a support for said element, an ionizable gas surrounding said element, and a plate of insulating material mounted on said support and provided with an opening-through which said element passes, said element constituting the sole terminal source of the discharge.

CHESTER H. BRASELTON. 

